1. Field of the Invention
The present invention relates to a backlight chassis for a liquid crystal display panel.
2. Description of the Related Art
A backlight chassis holding a light source lamp as a backlight for a liquid crystal display panel is, in a case in which the liquid crystal display panel is a large one, typically formed of a metal sheet (specifically, a steel sheet) in view of strength and cost. An example of such a backlight chassis made of a metal sheet is disclosed in JP-A-2005-107499.
Although the backlight chassis disclosed in JP-A-2005-107499 has a ladder configuration, backlight chassis are also often formed to have a tray configuration. A backlight chassis having a tray configuration has an increased size and suffer the following disadvantages.
That is, so called “oil canning”, in which the center of a metal sheet is popped back or forth so as to be warped, occurs. In some cases, the center of a metal sheet is even warped to be as much as several millimeters deviated from the planned geometric plane. The thus-structured backlight chassis generates abnormal noise (chattering noise) when it receives vibration. In addition, a light source lamp (e.g., a cold-cathode tube) incorporated in such a backlight chassis is of a long length, and thus, when vibration (for example, acoustic vibration of a television speaker) is transferred thereto, the light source lamp makes noise. To avoid such noise, the center portion of the light source lamp is fixed to the backlight chassis with a clip. However, if a large impact is received due to the occurrence of oil canning, the engagement between the light source lamp and the clip may be released. If the engagement is not released, the light source lamp itself will be warped, and as a result, a crack may occur in the lamp, or the distance between the lamp and the liquid crystal display panel may become non-uniform to cause non-uniform brightness. To cope with these problems, a large number of backlight chassis are provided with a reinforcement metal fitting on the rear surface thereof to reduce oil canning.